Arrangement for receiving predetermined trains of electric impulses



- Sept. 3, 1946.

ca. :2. HARTLEY ET AL 2,406,834 ARRANGEMENT FOR RECEIVING PREDETERMINED TRAINS OF ELECTRIC IMPULSES Filed May 28 1943 3 Sheets-Sheet 1 FIG. 3A

INVENTORS GEORGE CLIFFORD HARTLEY LEONARD POWELL LOWRY FREDRICK HARRY BRAY ATTORNEY Sept. 3, 1946.

G. c. HARTLEY ET AL.

ARRANGEMENT FOR RECEIVING PREDETERMINED TRAINS OF ELECTRIC IMPULSES Filed May 28, 1945 3 Sheets-Sheet 2 Sept. 351946. a, c, HARTLEY AL 2,406,834 ARRANGEMENT FOR RECEIVING PREDETERMINED TRAINS OF ELECTRIC IMPULSES Filed May 28, 1943 :5 Sheets-Sheet s INVENTORS GEORGE CLIFFORD HARTLEY LEONARD POWELL LOWRY FZEIDRICK HARRY BRAY ATTORNEY Patented Sept. 3, 1946 ARRANGEMENT FOR RECEIVING PREDE- TERMINED TRAINS OF ELECTRIC IM- PULSES George Clifiord Hartley, Leonard Powell Lowry, and Frederick Harry Bray, London, England, assignors to Standard Telephones and Cables Limited, London, England, a British company Application May 28, 1943, Serial No. 488,868 In Great Britain June 4, 1942 12 Claims. 1

This invention relates to a device for periodically opening and closing an electric circuit.

An object of the invention is to provide such a device the periodicity of which is independent of fluctuations of the supply.

According to the invention a device for periodically opening and closing an electric circuit comprises a polarised relay having two opposed windings, means for passing current through one winding, means for passing the charging current of a condenser through the other winding, contacts controlled directly or indirectly by the relay to change the direction of current through the one winding and to start the discharge of a condenser through the other winding, and contacts controlled directly or indirectly by the relay for opening and closing said circuit.

Preferably adjustable resistances are provided associated with the relay windings for adjusting the period of a complete make and break of the circuit being controlled and the ratio between make and break.

The invention also comprises the use of a device as set out above in selective apparatus adapted to respond to signals consisting of a sequence of marks and intervening spaces of prescribed duration. One of such devices supplies impulses to a relay counting chain for measuring the duration of the marks, another supplies impulses to a second relay countin chain for measuring the duration of said spaces. Means controlled by the relay counting chains returns the apparatus to zero upon the occurrence of a mark or space of other than prescribed duration, and means controlled by the relay counting chains closes a circuit upon the occurrence of the correct sequence of marks and spaces.

The invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows a circuit and the parts connected therein which form the device according to the invention;

Fig. 2 shows curves for explaining the operation of Fig. 1;

Figs. 3A and 3B taken together show the circuit of a radio distress signal receiver, responding to a distress signal to give an alarm but not so reponding to other signals;

Fig. 4 is a timing diagram for certain relays of Fig. 3.

Referring to Fig. 1 of the drawings, the circuit shown is adapted to remain in the condition shown until a relay ST is operated. Relay P is a polarized relay with two windings. Current is normally flowing from battery B through a potentiometer PR to ground. Current also flows from a point on the potentiometer, through winding I of relay P, back contacts ppI, back contacts stI, ground. This current is adjusted to be sufficient to keep the armature of relay P against its spacing contact S, in which position relay PP is de-energised. Contacts $752 back, keep a condenser C short circuited through a resistance Rs.

When it is desired to start the periodic operation of relay P, relay contacts stI change over and contacts stZ open, due to operation of relay ST. Current then flows from battery B through resistance R4, front contacts stI, back contact-s ppl, winding I of relay P, point 'on potentiometer PR, ground. This current tends to move the armature of relay P to its marking contact, but the effect is opposed by that of a charging current for condenser C flowing through resistances R4 and R3, winding 2 of relay P.

Curve A in Fig. 2 shows the variation of the current in winding I with time, and curve B the variation of current in winding 2 with time. The line cIcI represents the current necessary to operate the armature of relay P to its marking contact. As the currents in the two windings are opposed, this operation of the armature does not take place until time tI when the difference has become equal to ccI.

When relay P closes its marking contact M, relay PP is operated and contacts ppI change over. The current in winding I of relay P changes direction, flowing now from a point on potentiometer PR through winding I of relay P, contacts ppl to ground. This current tends to move the armature of relay P to its spacing contact. The condenser C commences to discharge through winding 2 of relay P and the discharge current opposes the current in winding I. The armature of relay P is thus not operated to its spacing contact until time t2.

Any variation of voltage of battery B will affect the current in each winding in the same manner, either on operation of marking or spacing contacts, so that such variation does not affect either the overall period of operation of relay P nor the ratio between the periods of closure of marking and spacing contacts.

Contacts of relay PP (not shown) may be used to open and close a circuit.

The point at which winding I of relay P is connected to potentiometer PR, and the values of resistances R3, R4 and the capacity of condenser C may be altered in order to alter the a overall period of relay P and the ratio between the periods of opening and closing of a circuit by contacts of relay PP.

The device above described may be used to produce makes and breaks of an electric circuit (impulses) for any purpose for which exact timing is important. Figures 3A and 313 as applied to a radio distress signal receiver. A marine distress signal consists of a eries of three dashes each of four seconds in length separated by spaces of one second duration. A certain tolerance in the length of dashes and spaces is allowed in distress signal receivers and a dash is accepted as of correct length if between 3.5 seconds and 4.5 seconds duration, whilst a space is accepted as correct if it exceeds second approximately and does not exceed 1% seconds.

In the circuit shown in Figures 3A and 3B, rclays P and PA are used, the circuits of which give an impulse time (make or break) of approximately 580 milliseconds with make and breaks equal. The following four batteries shown by the conventional symbols of thick and thin lines are 120 volts; in Figure 3A the battery attached between ground and the terminal ST2, in Figure 3Bthe one attached between the resistor RI and ground, in the same figure the one attached between R5 and ground, and in the same figure the one attached between the terminal PFZ and ground. These are used to feed the circuits of the polarized relay P and PA. The other batteries also shown by the same conventional sy1rbols of thick and thin lines are 24 volts.

The terminal marked RC is connected to a relay in the output circuit of a radio receiver suchmanner that when a relay in the latter circuit responds to a dash battery i applied to terminal RC to operate relays R and HR whilst during'a space the battery i removed. On receipt of a correct distress signal, the circuit shown applies ground to terminal AA to operate audible alarm.

The circuit is not in use until a locking key KSI is operated.

The key KSI prepares a circuit for a start relay ST. When a dash is received and battery is applied to terminal RC a circuit is completed for relays R and HR over to! back, saI back, tbI back, sbl back, tel back, scI back, st l' back, ground. Relay HR is a high speed relay and closes a locking circuit of R and HR to ground over hrI. R is a slow operating relay, having one winding shunted by it own back contacts. These relays are so arranged that relay HR releases within 1 millisecond if battery is removed from terminal RC, whilst relay R being slow to operate is not energised due to accidental signals. Relay R when. energised removes the short circuit from it second winding and becomes fast to release.

At contacts r2 a. circuit is closed for relay ST from battery, r2 front, winding of ST, n2 back andLI back in parallel, key KSE, round. When ST operates, contacts sti change over the circuit for winding I of relay P, contacts st2 remove a short circuit from condenser CI in the circuit of winding 2 of relay P, contacts std prepare a cir-- cuit for counting relays TA, etc., and contacts st4 open the circuit of R and HR which, however, remain closed at hrI front until the signal comes to an end.

The circuit of relay P i like that of relay in Fig. 1.. Current flows from the 120 volt battery over resistances RI and R2 to ground on In particular it is shown in key KSI. Before relay SR operates current flows from a point between resistances RI and R2 through winding I of relay P, prl back, stI back, ground. When relay ST hasoperated, current flows from 120V battery, stl front, prl back, Winding I of relay P, resistance R2, key KSI, ground. Charging current for condenser CI flows over stI front, prl back, resistance R3, winding 2 of relay P, condenser CI, key KSI, ground. For production of impulses of the desired period, viz: 580 milliseconds with about ratio relay P is a telegraph relay of the kind described in British specification No. 491,893, condenser CI is 10 microfarads, RI is 60,000 ohms, R3 is 30,000 ohms, whilst R2 is adjustable between 25,000 and 30,000 ohms.

After an interval relay P closes its marking contact and operates a helping relay PP which at contacts pp! operates a second helping relay PR. At contacts ml 'the current in winding I of relay P i reversed and the condenser charging circuit broken. At contacts 2on2 relay SA is operated from battery winding 2 of SA, ta2 back, 2 2 2 front, 3153 front, ground.

The counting relays SA, TA, SB, TB, SC, TC are operated and released by the closing and opening of contacts 17192, as determined by the closing and opening of the marking contact pl, in a sequence which is used to time the period of a dash. The circuit for these counting re lays is dependent upon contacts st3 being closed; when these contacts open all the said counting relays are released. The sequence of operation of the counting relays can be seen from Fig. 4. Horizontal lines indicate the periods during which the respective relays are operated.

When relay P opens its marking contacts, relay PP releases followed by PR. During a very brief interval whilst back contact-s p204 areclosed and before front contacts p12 are opened a short circuit of condenser Cl' exists to drain off any residual charge therefrom.

When relay PP releases, relay TA operate in series with winding I of relay SA, the circuit be- 45 ing completed over sa2 front, @1102 back. A noninductive shunt around winding 2 of relay SA ensures that contacts saZ remain closed during possible vibration of contacts 1119?. SA remains operated. Relay TA completes, at contacts tat-l front a circuit for Winding I of relay SB, which relay operates.

When relay PP again operates av circuit for rela TA is completed, independently of relay SA, over 25112 front and p102 front and relay TA remains operated but relay SA releases. Relay SB remains operated.

When relay PP releases for the second time relay TA is released and relay TB is operated in series with winding I of relay SB. Relay SC operates over winding 2 and tbl front.

When relay PP operates. for the third. time, relay SA again operates and the above described sequence of operation and release of relays SA and TA continues to occur in subsequent periods. The pairs of relays SB and TB and SC and TC operate and release similarly to relays SA and TA, their cycles of operation depending upon cont-acts of TA and TB respectively instead of upon contacts of PP.

It will be seen from Fig. 4 that the periods of operation and release of relays SA and TA are twice those of relay PP and in consequence the periods of operation and release of relays SB and TB are twice those of relay TA and the periods of operation and release of SC and TC twice those of TA.

After relay PP has released after its sixth operation, i. e., after a period of approximately 3.5 seconds, relays SB, TB and TC are all operated and relay D operates over tc3 front, .9112 front, tb2 front, st3 front, ground, and locks over 113 front, st3 front to ground. Relay D prepares a circuit for relay PZ over pzl back, all front, in series with ST, but remains short circuited whilst relay R is operated.

If the dash ceases after the termination of the sixth operation of PP (and before the end of a certain limiting period as explained hereafter), relay PZ operates in series with relay ST. Relay PZ closes a locking circuit for itself over pzl front, qal back, ral back and rbl front in parallel, keys KS, ground and breaks the circuit for ST which releases.

If the received dash lasts longer than the eighth period of operation of PP, i. e., longer than 4.5 seconds approximately, relay DD operates over (12 front, tc2 back, fbZ back, st3 front, ground and breaks the operating circuit for P2. Relay DD looks over dd2 front to st? front and ground. Thus whilst the dash continues further relay PZ cannot operate. If then the dash ceases after 4.5 seconds, relay ST releases, its circuit bein broken at contacts 12 and the whole of the circuits return to normal condition.

Relay P2 is the relay, the energisation of which indicates that a dash of correct duration has been received.

After the release of ST and the return to normal of the counting relays SA, etc, a circuit is again completed from ground over std back, so! back, tcl back, sbl back, tbl back, sal back, tal back for relays R and HR to respond to any further dash. Any short signals received, clue to atmospherics, in the pause between dashes, are unlikely to operate relay ST.

The pause between dashes must now be measured and the end Of the phase is signalled by the re-operation of relay ST and the end of a pause of correct duration by the re-operation of relay ST whilst relay P2 is still operated. The minimum period allowed for a correct pause is the period within which PZ operates, ST releases, the counting relays SA, TA, etc, release and relay ST re-operates completely. The maximum time allowed for a correct pause is 1.5 seconds approximately and is timed by the response of counting relays QA, RA, QB and RB, to impulses produced by relay PA the circuits of which are arranged in the same manner as those of relay P. Contacts p22, on changing over change over the circuits of relay PA and contacts p.25 prepare circuits for counting relays QA, RA, QB and RB.

After an interval relay PA closes its marking contacts pal, and operates relay PT. Front contacts p752 complete a circuit for relay QA over winding 2. Relays QA, RA, QB and RB operate and release in the same manner and at the same intervals as relays SA, TA, SB and TB and their sequence of operations is shown in the lower part of Fig. 4. At the end of the third operation of relay PT, relays QA, RA and RB are all in operated condition and the circuit of PZ is broken at contacts qal, ml and Th! in parallel and PZ releases. Release of P2 stops the operation of relay PA and also releases the counting relays QA, RA, QB and RB so that the circuit is in the same condition as before the receipt of any signals.

When PZ first operated, a circuit was completed for relay L, battery, winding 2 of relay L, m2 back p24 front p23 front, key KS ground. Relay L prepares a circuit for relay M and when PZ releases, relay M operates in series with winding l of relay L, 23 front, p24 back, st2 front, key KS, ground. If relay PZ releases before ST operates, however, this circuit is not completed and relay L releases.

Relays L and M operated together therefore record the conclusion of a correct pause period immediately after the first correct dash period.

Relay ST restores the circuits of relay P and relay PP commences impulsing as before, the number of these impulses bein counted by the counting relays SA etc. in the same manner as before. It should be noted that PZ is not immediately released upon the operation of relay ST, but that relays PA and PT go on impulsing and after these impulses PZ is released in time for its re-operation when required on a dash exceeding 3.5 seconds. Then in the same manner as above described relay PZ operates if the second dash period is of correct length. On this operation, a circuit is completed for relay M independently of relay L over m2 front, p24 front, p23 front, KS, ground. Relay L releases. Relay N then operates over Z2 back, ml front, p.23 front, KS, ground; and locks over 11.3 front and the same circuit.

If relay PZ is prevented from operating because the dash lasts too long, the circuit for relays M and L in series over 1024 back, and s't2 front is broken when ST releases at the end of the dash period and relays M and L are released. The operation of relay N is thus a record that a second dash of correct duration has been received.

When PZ operates relays PA and PT begin impulsing as before to time the pause period, If ST re-operates before the pause has lasted long enough to release PZ the locking circuit for relay N goes over 113 front, st2 front, key KS, ground. If, however, the pause lasts too long, so that PZ is released before relay ST operates the locking circuit of relay N is broken and that circuit releases.

The re-operation of ST starts relays P and PP impulsing to time the third dash. If this third dash is of correct length, PZ re-operates and relay L operates over m2 back and its original circuit. A circuit is now closed for relay N over Z2 front, 122 front, key KS, ground. Relay L is also held operated either over 1122 back, p24 front, or in series with M over 13 front and 1124 back, n3 front and the same locking circuit as relay N. Ground from key KS is extended over ll front, n! front to terminal AA to give an audible alarm.

The periods of pulsation of relays P and PA may be set to the correct value by adjustment of resistances R2 R6. In order to provide for a check of the periods of these relays test keys KT! and KT2 are provided. Key KT2 when operated causes the operation of relay R, fol- V lowed by that of ST and the pulsing of relays P and PP. Key KTI when operated causes the operation of relay PZ and the consequent pulsing of relays PA and PT. The impulses of contacts p p3 or p133 operate a counting meter CM when key KT3 or KT4 is closed. The adjustment required is such that for relays P and PP the meter should be operated between 102 and 105 times a minute, whilst for relays PA and PT the meter should be operated between and 124 times a minute.

What is claimed is:

1. In an automatic signaling system, alpolarized relay having an armature electromagnetically controlled by two opposite windings each establishing any one of two switching positions in accordance with current polarity, a first circuit means connected to one of said windings, means for supplying current to said first circuit means, a second circuit means connected to the second of said windings and comprising capacitance means, meansfor supplying current to said second circuit means to cause charging of said capacitance means, a first switching means controlled. by said relay for reversing the direction ofcurrent in said first circuit means and for discharging said capacitance means in said second circuit means, anda second switching means controlled bysaid. relay to open and close periodically in accordance with the charging and discharging of said capacitance means.

2. In an automatic signaling system, a polarized relay having an armature electromagnetically controlled by two opposite windings each establishing any one of two switching positions in accordance with current polarity, a first circuit means connected to one of said windings, means for supplying current to said first circuit means, a second circuit means connected to the second of said windings and comprising capacitance means, means for supplying current to said second circuit means to cause charging of said capacitance means, a first switching means controlled by said relay for reversing the direction or current in said first circuit means and for discharging said capacitance in said second circuit means, a second switching means controlled by said relay to open and close periodically in accordance with the charging and discharging of said capacitance means, and a third switching means for selectively maintaining said capacitance means in a steady state while maintaining a holding current through the winding not connected with said capacitance means.

3. In an automatic signaling system, a polarized. relay having an armature electromagnetically controlled by two opposite windings each establishing any one of two switching positions in accordance with current polarity, a first circuit means connected to one of said windings, means for supplying current to said first circuit means, means for adjusting the current of said winding to vary operation and release times of said relay, a second circuit means connected to the second of said windings and comprising capacitance means, means for supplying current to said second circuit to cause charging of said capacitance means, a first switching means controlled by said relay for reversing the direction of current in said first circuit means and for discharging said capacitance means in said second circuit means, and a second switching means controlled by said relay to open and close periodically in accordance with the charging and discharging of said capacitance means.

4. In an automatic signaling system, a polarized relay having an armature electromagnetically controlled by two opposite windings each establishing any one of two switching positions in accordance with current polarity, a first circuit means connected to one of said windings, means for supplying current to said first circuit means, means comprising a potentiometer for adjusting thecurrent of said winding to vary. operationand release times of said relay, a second circuit means connected to the second of said windings. and

comprising. capacitance'means, means for supplying current to said second circuit means to cause charging. of saidv capacitance means, a first switching means-controlled by said relay for reversing the direction of current in said first circuit means and for discharging said capacitance means in saidsecondcircuitmeans, and a second switching means controlled by said relay to open and close periodically in accordance with the charging and. discharging. of said capacitance means.

5. A system according to claim 1, comprising means for maintaining said capacitance means ina steady state and maintaining a holding current through the winding of therelay not con.- nected to said capacitance-means, to render the system inoperative.

6. A system according to claim 4, in which said one winding is connected to a point on said potentiometer whereby the current in said: winding is. adjustable to vary at least one of the following characteristics: the ratio, between the time of operation and release of saidpolarized relay, and the complete period of operation and release.

7. A system according to claim 1, comprising means for operating said first and second circuit means in accordance Withllll duration oila signal received, a series of counting relayslsuccessively operated by a number of successive timing impulses produced by said secondswitching. means for the duration of saidsignal, relay means for evaluating a signal of. predetermined duration, and circuit means for energizing said relay means, including preparing contacts. and operating contacts, said preparing contacts being operated by a counting relay corresponding to the passage of a predetermined number of timing impulses, and said operating contacts being operated by the ceasing of the signal producing said timing impulses.

8. A system according to claim 1, comprising means for operating said. first and second circuit means in accordance with the duration of a signal received, a series of counting relays successively r operated by a number of successive timing impulses produced by said second switching means for the duration of said signal, relay means for evaluating a signal of predetermined duration, circuit means for operating said relay means, including preparing contacts and operating contacts, said preparing contacts. being operated by a counting relay corresponding to the passage of a predetermined number of timing impulses, and said operating contacts being operated by r the ceasing of the signal producing said timing impulses, and further relay means operated by a counting relay after the passage of a predetermined number of? timing impulses greater than the foregoing one, and for restoring the polarized relay into the same state as before the reception of a signal.

9. A system according to claim 1, comprising means for operating said first and second circuit means in accordance with the duration of a signal received, a series of counting relays successively operated by a number of successive timing impulses produced by said second switching means for the duration of said signal, relay means for evaluating a signal varying in duration between predetermined limits, further circuit means for operating said relay means, said further circuit means including preparing contacts and operating contacts, said preparing contacts being operated by a counting relay corresponding to the passage of a predetermined number of timing impulses, and said operating contacts being operated by the ceasing of the signal producing said timing impulses, and further relay means operated by a counting relay corresponding to the passage of a predetermined number of timing impulses greater than the foregoing one, for restoring the polarized relay into the same state as before the reception of the signal, the difference between the first and second numbers of timing impulses being two timing impulses and equal to the tolerance permissible for the duraion of a signal.

10. In an automatic signal system according to claim 1, comprising a second polarized relay having an armature electromagnetically controlled by two opposite windings and establishing any one of two switching positions in accordance with current polarity, relay means operating said second polarized relay and controlled by the second switching means of the first polarized relay in response to a normal duration dash signal controlling its first and second circuit means, said second polarized relay having first and second circuit means connected to its two windings, respectively, one of said circuit means comprising capacitance means, said circuit means being controlled by a pause received succeeding said normal duration dash, further switching means controlled by said second polarized relay to open and close periodically in accordance with the charging and discharging of the capacitance means of said second polarized relay, a series of counting relays successively operated by a number of successive timing pulses produced by said further switching means for the duration of said pause, relay means for evaluating a pause of predetermined duration, and further circuit means for energizing said relay means, said further circuit means including preparing contacts and operating contacts, said preparing contacts being operated by a counting relay corresponding to the passage of a predetermined number of timing impulses, and said operating contacts being operated by the ceasing of the pause producing said timing impulses.

11. In an automatic signal system according to claim 1, comprising a second polarized relay having an armature electromagnetically controlled by two opposite windings and establishing any one of two switching positions in accordance with current polarity, relay means operating said second polarized relay and controlled by the second switching means of the first polarized relay in response to a normal duration dash signal controlling its first and. second circuit means,

ing capacitance means, said circuit means being controlled by a pause received succeeding said normal duration dash, further switching means controlled by said second polarized relay to open and close periodically in accordance with the charging and discharging of the capacitance means of said second polarized relay, a series of counting relays successively operated by a number of successive timing ulses produced by said further switching means for the duration of said pause, relay means for evaluating a pause of predetermined duration, further circuit means for operating said relay means, said further circuit means including preparing contacts and operating contacts, said preparing contacts being operated by a counting relay corresponding to the passage of a predetermined number of timing impulses, and said operating contacts being operated by the ceasing of the pause producing said timing impulses, and further relay means operated by a counting relay after the passage of a predetermined number of timing impulses greater than the foregoing one, and for restoring the polarized relay into the same state as before the reception of a signal.

12. In an automatic signal system according to claim 1, comprising a second polarized relay having an armature electromagnetically controlled by two opposite windings and establishing any one of two switching positions in accordance with current polarity, first relay means operating said second polarized relay and controlled by the second switching means of the first polarized relay in response to a normal duration dash signal controlling its first and second circuit means, said second polarized relay having first and secone circuit means connected to its two windings, respectively, one of said circuit means comprising capacitance means, said circuit means being controlled by a pause received succeeding said normal duration dash, further switching means controlled by said second polarized relay to open and close periodically in accordance with the charging and discharging of the capacitance means of said second polarized relay, second relay means controlled by said further switching means in response to a normal duration pause, said first and second relay means including counting relays for registering the number of succeeding dashes and dots of correct duration, and alarm means controlled by at least one of said counting relays in response to the registration of a predetermined number of correct dashes separated by correct dots.

GEORGE CLIFFORD HARTLEY. LEONARD POWELL LOWRY. FREDERICK HARRY BRAY. 

